Ice-cream confectionery product and a method for its manufacture

ABSTRACT

Ice cream confection normally in liquid state which is an oil-in-water emulsion containing fats, milk proteins, sweetness and water. The water is made physically and chemically stable by means of a stabilizing and thickening composition of an alginate, a disodium phosphate and a modified starch. The product is made by preparing the emulsion, sterilizing and homogenizing to obtain a product having a viscosity of not greater than 1200 cps. Even without the product has a homogeneously microcrystalline structure after freezing.

The present invention relates to a fluid, edible composition, adapted tobe frozen, which may be stored in unfrozen condition for an extendedperiod of time, and which is to be frozen in a refrigerator to give asolid ready-to-eat ice-food product.

Particularly the invention relates to a product having a fat content of10 to 18% wt typical of products defined as ice-cream as distinct fromice-milk, sherbet and ice.

Ice-cream is an edible composition comprising milk, cream or water,sweetening agents, flavourings, binders and emulsifiers, which is to bebrought to a solid or semi-solid state by freezing.

It is conventional in ice-cream preparation to cause air to beincorporated in the composition during or before freezing, in order toobtain a peculiar, pleasant mouth feeling when the frozen composition iseaten. Owing to the presence of small air bubbles, the ice-cream meltsrapidly in the mouth giving a pleasant freshness fealing to the consumerand avoiding an undesirable too strong cooling of the mouth and teeth.

Ice-cream is sold in a ready-to-eat condition, that is, it is stored inpackaged or open condition under refrigeration and is directly taken outof the refrigerated environment just before being eaten. When ice creamis bought, the consumer has therefore to act so as to avoid thawing ormelting of the packaged frozen composition, since upon thawing, asubsequent freezing would lead to a substantial change in theconsistency of the product, thereby loosing the typical physical andorganoleptic properties thereof. Particularly in summer time isdifficult to avoid thawing on the way from the refrigerating apparatusthe market place to the domestic refrigerator.

From DE-PS No. 26 57 489 it is known a package including a unfrozenedible composition to be frozed by the final user, which may be storedor carried at room temperature withouth need of a refrigeratingapparatus. Said package comprises a casing for the unfrozen mass with alid and a sealing foil which is germ and liquid tight; a stick beingembedded in the edible mass, whereby upon freezing the composition maybe eaten as "ice on a stick".

In DE-PS No. 23 29 816 there is disclosed a ice-composition comprising azone A and an adjacent fat containing solid zone B wherein zone Aconsists of a frozen aqueous composition of an edible mass and zone Bconsists of a homogeneous edible fat dispersion including fat and asugar containing acqueous syrup. The edible composition A includes adispersed gaseous phase, whereas the fat dispersion B, surrounding zoneA, contains fat homogeneous dispersed in the syrup and preferably doesnot contain a dispersed gaseous phase. Inverted sugar may be used toprepare zone B.

From FR-B No. 2,359,58 is known an ice cream including sucrose andinverted sugar which however is to be eaten upon having been beaten andwhipped in a ice-cream freezer.

From U.S. Pat. No. 4,264,637 it is known an edible composition in theform of an aqueous gel, adapted to be frozen, which is free of butyricfat, having a pudding consistency at room temperature.

The composition contains activated or peptized microcrystallinecellulose with carboxymethyl cellulose and/or alginate, and/or xanthangum and/or modified starch. Such product, which needs to include apreservative, has a chewy consistency when frozen which is far from thecreamy consistency of conventional ice-cream.

The object of the present invention is to provide a fluid ediblecomposition, which can be caused to solidify by freezing withoutmechanical beating to incorporate air, which does not present icecrystals perceptible to the consumer and having a fat content ofconventional ice cream and also presenting organoleptic properties andtexture similar to those of conventional aerated ice-creams.

A further object of the present invention is to provide a product whichis free from preservatives, which can be kept in the liquid state for aprolonged period of time, even at ambient temperatures, when packagedunder sterile conditions, and which is then stable both physically andchemically.

These objects are achieved by means of a product of the type specifiedin the preamble of the main claim, characterised in that it can be madeby the steps of:

(a) preparing an oil-in-water emulsion at a temperature of 55° to 65°C., comprising with reference to the weight of the emulsion:

of the order of 10 to 18% by weight of edible fats,

of the order of 1 to 5% by weight of milk proteins,

up to 32% by weight of sweeteners selected from the group of lactose,sucrose, fructose and mixture thereof,

of the order of 0.1 to 1.6% by weight of a stabilizing and thickeningcomposition including a salt which acts as a protein stabilizer, agelling agent constituted by an alkali metal alginate, and a thickeningagent selected from the group of chemically modified starches,

a quantity of liquid and/or solid flavourings, sufficient to give thedesired taste,

the balance to 100 being constituted by the aqueous phase,

(b) sterilising the emulsion at a temperature of 140° to 150° C. for aperiod of 15 to 2 seconds,

(c) homogenizing the sterilised emulsion at a temperature of 80° to 90°C. and a pressure of 70 to 200 bars, so as to give a product having aviscosity no greater than 1200 cPs, (measured at 20° C., Brookfieldviscosimeter) and

(d) cooling the product obtained for its subsequent packaging underaseptic conditions.

In the product according to the invention, the fat phase may beconstituted both by butyric fats and a mixture of butyric fats andvegetable fats. The butyric fats are preferably provided by the use ofwhole milk and cream in respective quantities of 20 to 45% by weight and15 to 40% by weight, with reference to the weight of the emulsion.However, the desired content of butyric fats could also be provided bythe use of cow's butter. The whole milk constitutes a basic element ofthe emulsion since it acts both as a solvent for the ingredients andbase element for the change of state. Furthermore, the milk, which formsthe continuous phase of the emulsion, contributes to the protein contentand to the lactose present in the emulsion. In addition, the creamcontributes to the fat phase, the protein content and the lactosecontent, completes the aqueous and the lactose content, completes theaqueous phase, and also adds to the taste. Naturally, the fat content ofthe emulsion could be adjusted by the addition of water to the emulsionitself.

When vegetable fats are used they are preferably chosen from oils havinga melting point between 30° and 60° C., such as, for example, coconutoil, palm oil and palm nut oil. Among these, fractionated coconut oil,that is the high melting fraction of coconut oil, is preferred, mainlybecause of its organoleptic characteristics. In this case, the ratio byweight of the butyric fats to the vegetable fats is preferably keptbetween 1:1 and 2:1.

By way of a sweetener, in addition to the lactose, the emulsiongenerally also contains a suitable quantity of a sugar constituted bysucrose and/or fructose. The use of fructose is particularlyadvantageous in that, by virtue of its low molecular weight, it lowersthe freezing temperature of the emulsion. Fructose is preferably used inquantities of 3 to 10% by weight of the emulsion. Moreover, the desiredsugar content could be completed by the use of condensed milk which alsocontributes, of course, to the protein content of the emulsion.

A further subject of the present invention is a thickening andstabilising composition for the preparation of the ice-cream foodproduct having the characteristics mentioned above, this compositioncomprising a chemically modified starch, an alkali metal alginate, and asalt as a protein stabilizer. The stabilising and thickening compositionpreferably includes 0.6 to 20 parts by weight of protein stabilizer saltand 6 to 300 parts by weight of alginate, per 100 parts of modifiedstarch. The preferred modified starch used is a starch acetate withadipic cross-linking (starch No. 14). The protein stabilizer salt ispreferably a disodium or dipotassium phosphate.

With reference to the weight of the emulsion which constitutes theconfectionery product according to the invention, the protein stabilizersalt is preferably used in quantities of 0.01 to 0.02% by weight, thealginate in quantities of 0.1 to 0.3% by weight, and the modified starchin quantities of 0.1 to 1.5% by weight.

The preparation of the emulsion is carried out at a typical temperatureof 55° to 65° C. and preferably at 60° C., such that the oil phase isliquid. The preparation is carried out in an emulsifier, for example ofthe agitator type rotated at about 1400 revolutions per minute, inaccordance with conventional methods for the preparation of emulsions.Milk preheated to about 60° C. is introduced into the emulsifier, afterwhich all the premixed dry soluble ingredients are added. The fat assuch, when used, is generally introduced last in the molten state.

The sterilisation step (b) is preferably carried out continuously bymeans of a scraped-surface heat exchanger (S.S.H.E.). In this step, theemulsion is kept at a temperature of 140° to 150° C. for a period of 15to 2 seconds under a hydraulic pressure sufficient to preventevaporation of the aqueous phase. It is preferable to carry out ahomogenisation upstream of the sterilisation step (b), at a temperatureof 55° to 65° C. and a pressure of 75 to 100 bars. Preferably, for thishomogenisation, a two-stage homogeniser is used in which thehomogenisation in the first stage is carried out at a pressure of 75 to100 bars and in the second stage at a pressure of 25 to 30 bars.

After sterilisation, the emulsion is cooled quickly to the temperatureof step (c), that is 80° to 90° C. This cooling may be effectedcontinuously with the use of a S.S.H.E. connected to the outlet of thesterilisation S.S.H.E. The final homogenisation step (c) is carried outat a pressure of 70 to 200 bars. Preferably, a two-stage homogeniser isalso used in this case, in which the homogenisation is carried out inthe first stage at a preferred pressure of 125 to 150 bars and in thesecond stage at a pressure of 25 to 30 bars. With the finalhomogenisation, the viscosity of the emulsion is adjusted to a value notgreater than 1200 cPs measured with a Brookfield RVT viscosimeter with aNo. 2 rotor at 50 rpm and at 20° C. Preferably the viscosity is adjustedwith the final homogenisation to a value of from 125 to 350 cPs measuredin the above conditions.

After the final homogenisation step (c), the emulsion is cooled to atemperature of 35° to 40° C. by means of a cooling S.S.H.E. and is thenfed to a storage tank in which it is kept under slight agitation, forsubsequent packaging under aseptic conditions. Naturally, all theoperation carried out downstream of the sterilisation step are carriedout under aseptic conditions.

The relatively low value of the viscosity of the product according tothe invention constitutes an important characteristic. In fact, it isfound that with a viscosity value within the limits indicated above, theformation of the desired microcrystalline structure is facilitated inthe frozen product. The product is generally packaged in asepticcontainers having a preferred volume of about 75 cc. The freezing pointof the product according to the invention is from -3° to -6° C.Preferably, the freezing is carried out by placing the product in anenvironment with a temperature which is 10° to 15° C. below the freezingpoint so as to ensure initial subcooling of the product. In fact, inthese conditions are found the best characteristics with regard to themicrocrystalline structure which is homogeneous and free from icecrystals perceptible by the consumer. The ice crystal dimension obtainedupon freezing in the product according to the invention is in the bestconditions in the range of 5-35 microns and never exceeds 150 microns.The drop time measured on a product initially at -20° C. and at leftroom temperature of 23° C., is from 15 to 18 minutes. The product can bekept in the liquid state for more than four months after packaging.Furthermore, it may be subjected to repeated freezing and thawing cycleswithout this prejudicing the stability of the emulsion and/or thequality of the frozen product when it is ready for eating.

The present invention will now be described in greated detail withreference to the following examples.

EXAMPLE 1

For the preparation of 100 Kg of product, an emulsion is prepared whichcontains the following ingredients:

    ______________________________________                                        whole milk            43.5 Kg                                                 cream                 26 Kg                                                   sucrose               21 Kg                                                   fructose              5.3 Kg                                                  coffee extract        3 Kg                                                    sodium alginate       0.12 Kg                                                 Na.sub.2 HPO.sub.4    0.015 Kg                                                NaCl                  0.04 Kg                                                 starch No.14          1 Kg                                                    ______________________________________                                    

The cream used has a butyric fat content of 50% by weight, a proteincontent of 2% by weight and a lactose content of 2.3% by weight.

The total fat, protein and sugar contents of the emulsion are given inTable 1.

For the preparation of the emulsion, the whole milk is preheated to 60°C. and introduced into the rotary emulsifier which has a speed of 1400revolutions per minute. The entire preparation of the emulsion iscarried out at a temperature of 60° C. The premixed soluble ingredientsare then introduced into the emulsifier under agitation and the cream,preheated to bring the fat to the molten state, is added last.

The coffee extract serves as the flavouring of the product and thesodium chloride enhances its taste.

The emulsion is then fed in a continuous system at temperature of 60° C.to a two-stage homogeniser, and is subjected to homogenisation at apressure of 80 bars in the first stage and 25 bars in the second stage.The homogenised emulsion is preheated in a S.S.H.E. to 110° C. and thenfed to a second S.S.H.E. in which the sterilisation is carried out at atemperature of 148° C. for 6 seconds. The flow of sterilised emulsion issubsequently procooled to 85° C. in a S.S.H.E. and then supplied to thesecond homogenisation stage in which it is kept at a pressure of 130bars in the first stage and a pressure of 25 bars in the second stage.After cooling in a S.S.H.E. to a temperature of 35° C., the flow ofemulsion is supplied to a storage tank and subsequently packaged inaseptic 75 cc containers.

The product obtained has a viscosity of 300 cPs determined by aBrookfield RVT viscosimeter with a No. 2 rotor at 50 rpm and 20° C.immediately after packaging. The viscosity of the product increasesslightly with time, but not such as to harm the freezing characteristicsof the product.

EXAMPLE 2

100 Kg of product are obtained by preparation of an emulsion comprisingthe following ingredients:

    ______________________________________                                        whole milk              40 Kg                                                 cream (Example 1 type)  26 Kg                                                 sucrose                 19.1 Kg                                               sweetened condensed milk                                                                              12.5 Kg                                               milk protein            1 Kg                                                  starch No.14            1 Kg                                                  sodium alginate         0.12 Kg                                               NaCl                    0.03 Kg                                               Na.sub.2 HPO.sub.4      0.013 Kg                                              flavourings             0.270 Kg                                              ______________________________________                                    

The total fat, protein and sugar contents of the emulsion obtained aregiven in Table 1.

The method for the preparation of the final product correspondssubstantially to that described with reference to Example 1. However,the sterilisation is carried out under slightly gentler conditions at atemperature of 144° C. for 6.5. seconds.

The final product has a Brookfield viscosity as previously defined ofabout 200 cPs, which increases slightly with time.

EXAMPLE 3

The product according to the invention is prepared in the same manner asdescribed with reference to Example 1, the following ingredients beingintroduced into the emulsifier:

    ______________________________________                                        whole milk             30.7 Kg                                                cream (Example 1 type) 12 Kg                                                  H.sub.2 O              24.5 Kg                                                fractionated coconut oil                                                                             7 Kg                                                   sucrose                10.7 Kg                                                fructose               8.5 Kg                                                 plain chocolate        3.6 Kg                                                 sodium alginate        0.3 Kg                                                 NaCl                   0.02 Kg                                                Na.sub.2 HPO.sub.4     0.01 Kg                                                starch No.14           0.2 Kg                                                 flavourings            2.4 Kg                                                 ______________________________________                                    

The total fat, protein and sugar contents of the emulsion are given inTable 1. The product obtained has a Brookfield viscosity as previouslydefined of about 350 cPs measured immediately after packaging.

In this case also, the product undergoes a slight increase in viscositywith time, but not such as to harm the structure of the frozen product.

                  TABLE 1                                                         ______________________________________                                                    Example 1                                                                             Example 2 Example 3                                       ______________________________________                                        Fats (% by weight)                                                                          14.5      15.5      14.1                                        Protein (% by weight)                                                                       2.0       3.0       1.3                                         Sugar (% by weight)                                                                         28.6      26.8      20.9                                        ______________________________________                                    

I claim:
 1. Ice-cream confectionery product which is in a liquid stateat ambient temperature and consists of a sterilised oil-in-wateremulsion comprising edible fats, milk protein, sweeteners and water, theemulsion being physically and chemically stable and preservable atambient temperature when packaged under aseptic conditions, having afreezing point of -3° to -6° C., and having a substantially homogeneousmicrocrystalline structure after freezing, even without beating, theproduct being prepared by a process comprising the steps of:(a)preparing an oil-in-water emulsion at a temperature of 55° to 65° C.,comprising with reference to the weight of the emulsion:about 10 to 18%by weight of edible fats, about 1 to 5% by weight of milk proteins, upto 32% by weight of sweeteners selected from the group of lactose,sucrose, fructose and mixtures thereof, about 0.1 to 1.6% by weight of astabilizing and thickening composition consisting essentially of aphosphate salt which acts as a protein stabilizer, a gelling agentconstituted by an alkali metal alginate, and a thickening agent selectedfrom the group of chemically modified starches, a quantity of ligandand/or solid flavourings sufficient to give the desired taste, thebalance to 100 being constituted by the aqueous phase, (b) sterilisingthe emulsion at a temperature of 140° to 150° C. for a period of 15 to 2seconds, (c) homogenizing the sterilised emulsion at a temperature of80° to 90° C. and a pressure of 70 to 200 bars, so as to give a producthaving a viscosity no greater than 1200 cPs, (measured at 20° C.Brookfield viscosimeter) and (d) cooling the product obtained for itssubsequent packaging under aseptic conditions.
 2. Product according toclaim 1, in which the edible fats comprise butyric fats and vegetablefats.
 3. Product according to claim 2, in which the ratio by weight ofthe butyric fats to the vegetable fats is from 1:1 to 2:1.
 4. Productaccording to claim 2, in which the vegetable fats are selected from thegroup consisting of fractionated coconut oil, palm oil, and palm nutoil, which have a melting point of 30° to 36° C.
 5. Product according toclaim 1, in which the fats are provided by the use of whole milk andcream in respective quantities of 20 to 45% by weight and 15 to 40% byweight of the emulsion.
 6. Product according to claim 1, in which theprotein stabilizing salt is a disodium or dipotassium phosphate inquantities of 0.01 to 0.02% by weight, with reference to the weight ofthe emulsion.
 7. Product according to claim 1, in which the modifiedstarch is present in quantities of 0.1 to 1.5% by weight, with referenceto the weight of the emulsion.
 8. Product according to claim 1, in whichthe modified starch is a starch acetate with adipic cross-linking. 9.Product according to claim 1, in which the alginate is present inquantities of 0.1 to 0.3% by weight, with reference to the weight of theemulsion.
 10. Product according to claim 1, in with the sweetenersinclude from 3 to 10% by weight of fructose, with reference to theweight of the emulsion.
 11. Product according to claim 1, in which step(a) is followed by a stage of homogenisation at a pressure of 75 to 100bars.
 12. Product according to claim 1, having in unfrozen condition aviscosity from 125 to 350 cPs (20° C. Brookfield viscosimeter). 13.Method for the preparation of an ice-cream confectionery product whichis in a liquid state at ambient temperature and consists of a sterilisedoil-in-water emulsion comprising edible fats, milk protein, sweetenersand water, the emulsion being physically and chemically stable andpreservable at ambient temperature when packaged under asepticconditions, having a freezing point of -3° to -6° C., and having asubstantially homogeneous microcrystalline structure after freezing,even without beating, the method comprising the steps of:(a) preparingan oil-in-water emulsion at a temperature of 55° to 65° C., comprisingwith reference to the weight of the emulsion:about 10 to 18% by weightof edible 25 fats, about 1 to 5% by weight of milk proteins, up to 32%by weight of sweeteners selected from the group of lactose, sucrose,fructose and mixtures theroef, about 0.1 to 1.6% by weight of astabilizing and thickening composition consisting essentially of aphosphate salt which acts as a protein stabilizer, a gelling agentconstituted by an alkali metal alginate, and a thickening agent selectedfrom the group of chemically modified starches, a quantity of liquidand/or solid flavourings sufficient to give the desired taste, thebalance to 100 being constituted by the aqueous phase, (b) sterilisingthe emulsion at a temperature of 140° to 150° C. for a period of 15 to 2seconds, (c) homogenizing the sterilised emulsion at a temperature of80° to 90° C. and a pressure of 70 to 200 bars, so as to give a producthaving a viscosity no greater than 1200 cPs, measured at 20° C.,Brookfield viscosimeter and (d) cooling the product obtained for itssubsequent packaging under sterile conditions.